Question about PIC code and GOT

Question about PIC code and GOT

[vincent Dupaquis]

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     Hello,

     I am doing PIC (Position Independant Code) code using the ARM 
compiler, and effectively try to avoid the creation of the GOT (Global 
Offset Table).

     I've got the feeling the GOT is not convinient and goes in opposite 
direction than the one we try to achieve with having PIC, at least this 
is the reason why I'm trying to avoid it.

     Any clue on the reason why it has been implemented that way ?

     I have got the feeling that its avoidable in all cases, even 
without going deep at assembly level.

     Regards,
         Vincent.

-- 

*Vincent Dupaquis*
Software security & Cryptography expert
06 24 58 17 05
/Europarc de Pichaury Bâtiment B8 1330 rue Guillibert Gautier de la 
Lauzière 13290 Aix-en-Provence/

www.trusted-objects.com <http://www.trusted-objects.com>


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Re: Question about PIC code and GOT

[Maciej W. Rozycki]

On Fri, 11 Jun 2021, vincent Dupaquis wrote:

>     I've got the feeling the GOT is not convinient and goes in opposite
> direction than the one we try to achieve with having PIC, at least this is the
> reason why I'm trying to avoid it.
> 
>     Any clue on the reason why it has been implemented that way ?

 Without going into processor-specific details, which may imply additional 
requirements, you need to have a place to store final load-time addresses 
of preemptible symbols, and GOT serves exactly that place.  The only case 
you could possibly be able to avoid, again barring any processor-specific 
requirements, the creation of a GOT with PIC code is a statically-linked 
position-independent executable (PIE).

 Late answer, but HTH.

  Maciej